Coaxial cable connector

FIELD OF THE INVENTION

[0001] The present invention relates to coaxial cable connectors and, more particularly, to a coaxial connector having an improved crimp section.

BACKGROUND OF THE INVENTION

[0002] Coaxial cable connectors are commonly used to terminate coaxial cables. These connectors typically include a conductive outer shell comprising a mating section, a signal pin and a cylindrical sleeve that receives and mechanically secures a stripped end of a coaxial cable. The coaxial cable has a center conductor for transmitting a signal. The center conductor is surrounded by a dielectric. An outer ground or shield conductor in the form of a pliant wire braid encircles the dielectric. The outer conductor is encased in a protective jacket.

[0003] To secure the coaxial cable in the connector, a stripped end of the coaxial cable is inserted into a receiving end of the cylindrical sleeve. The exposed center conductor is electrically connected to the signal pin contained within the connector. As the coaxial cable is inserted into the cylindrical sleeve, an inner tubular member, that may comprise raised barbs, is forced between the dielectric and the outer conductor of the coaxial cable. The outer conductor is received in a space between the cylindrical sleeve and the inner tubular member and may be folded back over the end of the protective jacket. This method and arrangement is disclosed in U.S. Pat. No. 5,499,934 issued to Jacobsen et al. and U.S. Pat. No. 5,525,076 issued to Down. A conventional crimping tool is then used to apply a crimp to the outside of the cylindrical sleeve securing the outer conductor jacket of the coaxial cable between the inner tubular member and the cylindrical sleeve.

[0004] A known alternative method for securing a coaxial cable in a connector is commonly used when larger connectors terminate smaller coaxial cables. In this method, a ferrule and an insulative cylinder, respectively, are positioned over the stripped coaxial cable before insertion into the cylindrical sleeve. The exposed center conductor is electrically connected to the signal pin within the connector. The outer conductor of the coaxial cable is then folded back and over the ferrule so that the outer conductor is received in a space between the cylindrical sleeve and the ferrule when the coaxial cable is inserted into the cylindrical sleeve. A conventional crimping tool is then used to apply a crimp along the outside diameter of the cylindrical sleeve to secure the outer conductor jacket of the coaxial cable between the ferrule and the cylindrical sleeve.

[0005] In these connectors, a compressive force applied by the crimp secures the internal components of the connector. This retention alone, however, is inadequate when external pulling forces are applied to the coaxial cable. For example, when an external force is exerted on the coaxial cable in a direction opposite from the connector body, the compressive forces are unable to prevent outward movement of the internal components. When the internal components become displaced, the integrity of the connector is jeopardized. Gaps created between the internal components also allow moisture and other foreign matter to enter the connector and may result in pin stubbing upon mating, further deteriorating the electrical performance of the connector.

[0006] It is therefore desirable to develop a coaxial connector with a rigid construction that improves coaxial cable retention and electrical performance by providing additional physical restraint of the internal components of the coaxial connector.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to develop an improved crimp section for a coaxial cable connector. This and other objects of the invention are achieved by a coaxial connector having a conductive outer shell comprising a mating section and a cylindrical sleeve. The cylindrical sleeve has a cable receiving end for receiving a cable, at least one ferrule located inside the cylindrical sleeve and an annular projection positioned on the cable receiving end of the cylindrical sleeve. The annular projection has a larger external diameter than the cylindrical sleeve. When a crimping die is applied to the cylindrical sleeve, the crimping die first contacts the annular projection, causing the annular projection to roll inward and toward the -mating section of the conductive outer shell to securely forward bias the cable and ferrule within the cylindrical sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention will now be described by way of example with reference to the accompanying figures in which:

[0009]FIG. 1 is an exploded perspective view of the coaxial connector.

[0010]FIG. 2 is a cross-sectional view of the coaxial connector before cable insertion and crimping.

[0011]FIG. 3 is a cross-sectional view of the coaxial connector including a terminated cable.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]FIG. 1 shows a coaxial cable connector <b>10</b> having an electrically conductive outer shell <b>12</b> comprising a mating section <b>12</b><i>a </i>and a cylindrical sleeve <b>12</b><i>b. </i>The mating section <b>12</b><i>a </i>has a centrally located signal pin <b>15</b> surrounded by a dielectric <b>18</b>. An retaining ring <b>17</b> is positioned between the outer shell <b>12</b> and the dielectric <b>18</b>. The mating section <b>12</b><i>a </i>may optionally comprise a fastener (not shown) that surrounds the conductive outer shell <b>12</b>, such as an internally threaded nut, designed to secure a complimentary receptacle to the mating section <b>12</b><i>a </i>of the end connector <b>10</b>. The cylindrical sleeve <b>12</b><i>b </i>has a cable receiving end <b>34</b> and an annular projection <b>11</b>. The cylindrical sleeve <b>12</b><i>b </i>receives a coaxial cable <b>20</b> for termination within the connector <b>10</b>. The coaxial cable <b>20</b>, shown in FIG. 1, has a center conductor <b>21</b> for transmitting a signal. The center conductor <b>21</b> is a solid or stranded wire that is centrally located within a dielectric <b>22</b>. An outer conductor <b>23</b> or shield surrounds the dielectric <b>22</b>. The outer conductor <b>23</b> generally comprises a pliant wire braid that may be woven over a foil sheath. The outer conductor <b>23</b>, encircling the cylindrical dielectric <b>22</b>, is encased within a protective jacket <b>24</b>.

[0013] Each of the major components will now be described in greater detail with reference to FIGS. 1 and 2. As shown in FIG. 2, the conductive outer shell <b>12</b> has a mating end <b>32</b> and a cable receiving end <b>34</b> disposed opposite the mating end <b>32</b>. An outer surface <b>36</b> extends from the mating end <b>32</b> to the cable receiving end <b>34</b>. The conductive outer shell <b>12</b> consists mainly of a mating section <b>12</b><i>a </i>and a cylindrical sleeve <b>12</b><i>b. </i>Within the mating section <b>12</b><i>a, </i>the outer surface <b>36</b> is contoured to have raised portions <b>40</b> and recessed portions <b>42</b> disposed therebetween. Moving rearward from the mating section <b>12</b><i>a, </i>an annular ridge <b>44</b> is disposed about the outer surface <b>36</b> rearward of the raised portion <b>40</b>.

[0014] The cylindrical sleeve <b>12</b><i>b </i>is disposed between the annular ridge <b>44</b> and the cable receiving end <b>34</b>. The cylindrical sleeve <b>12</b><i>b </i>consists of a generally tubular section having a cylindrical sleeve inner surface <b>54</b> and a cylindrical sleeve outer surface <b>56</b>. An annular projection <b>11</b> is disposed around the cylindrical sleeve outer surface <b>56</b> at the cable receiving end <b>34</b>. It should be understood by those reasonably skilled in the art that while the annular projection <b>11</b> is shown here as having a generally rectangular cross section it could have other geometrical configurations either on the outer surface <b>56</b> or the inner surface <b>54</b> that may have a similar function as will be described in greater detail below. Also, it should be understood by those reasonably skilled in the art that while the outer surface <b>36</b> has been described with a certain contour, that contour may be varied depending on size constraints and securing requirements of a particular application.

[0015] Beginning once again at the mating end <b>32</b> in FIG. 2, the conductive outer shell <b>12</b> has a receptacle receiving portion <b>46</b> disposed along an inner surface <b>38</b>. The inner surface <b>38</b> extends from the mating end <b>32</b> to the cable receiving end <b>34</b>. A ring receiving portion <b>48</b> is located along the inner surface <b>38</b> rearward of receptacle receiving portion <b>46</b> and has a slightly smaller inner diameter than the receptacle receiving portion <b>46</b>. A dielectric receiving portion <b>50</b> is located rear of the ring receiving portion <b>48</b> and has a slightly smaller diameter than the ring receiving portion <b>48</b>. The dielectric receiving portion <b>50</b> ends at a rear wall <b>52</b> that connects with a cylindrical sleeve inner surface <b>54</b>. The cylindrical sleeve inner surface <b>54</b> is generally cylindrical and has a relatively smaller diameter than the dielectric receiving portion <b>50</b>. The cylindrical sleeve inner surface <b>54</b> extends from the rear wall <b>52</b> back to the cable receiving end <b>34</b>.

[0016] A dielectric <b>60</b> is located within the dielectric receiving portion <b>50</b> at the mating end <b>32</b> of the connector <b>10</b> and has a diameter smaller than the inner surface <b>38</b>. The dielectric <b>60</b> extends to the rear wall <b>52</b>. The receptacle guide <b>60</b> has an inner receptacle receiving portion <b>58</b>. A signal pin receiving portion <b>62</b> is located within the dielectric <b>60</b> is open its rear end and extends to an insulative cylinder receiving portion <b>84</b>. Located on the signal pin receiving portion <b>62</b> is an annular stop wall <b>64</b> that transitioning to the larger circumferencial area of the insulative cylinder receiving portion <b>84</b>.

[0017] The signal pin <b>15</b> is centrally located within the inner receptacle receiving portion <b>58</b>. The signal pin <b>15</b> has a coupling portion <b>15</b><i>a </i>and a signal pin body <b>15</b><i>b. </i>The coupling portion <b>15</b><i>a </i>of the signal pin <b>15</b> extends to a wall <b>16</b> of the signal pin body <b>15</b><i>b. </i>The signal pin body <b>15</b><i>b </i>is hollow and has a larger diameter than the coupling portion <b>15</b><i>a. </i>

[0018] An insulative cylinder <b>14</b> has an insulative cylinder inner surface <b>72</b>, and insulative cylinder outer surface <b>66</b> extending between first and second ends <b>68</b>, <b>70</b>, respectively. The insulative cylinder inner surface <b>72</b> has a diameter smaller than the diameter of the insulative cylinder outer surface <b>66</b>. The diameter of the insulative cylinder outer surface <b>66</b> is smaller than the cylindrical sleeve inner surface <b>54</b> such that a small clearance exists between the insulative cylinder outer surface <b>66</b> and the cylindrical sleeve inner surface <b>54</b>. The insulative cylinder first end <b>68</b> is positioned adjacent to the signal pin body <b>15</b><i>b. </i>The insulative cylinder second end <b>70</b> is positioned adjacent a conductive ferrule <b>13</b>.

[0019] The ferrule <b>13</b> is generally cylindrical and has a ferrule outer surface <b>74</b>, a ferrule inner surface <b>76</b>, extending between first and second ends <b>78</b>, <b>80</b>, respectively. The ferrule inner surface <b>76</b> has a diameter smaller than the ferrule outer surface <b>74</b>, but larger than the insulative cylinder inner surface <b>72</b>. The ferrule outer surface <b>74</b> has a diameter which is smaller than the inner diameter of the cylindrical sleeve inner surface <b>54</b>, but slightly larger than the insulative cylinder outer surface <b>66</b> such that the clearance <b>19</b> between the ferrule outer surface <b>74</b> and the cylindrical sleeve inner surface <b>54</b> is slightly smaller than between the insulative cylinder <b>14</b> and the inner diameter <b>54</b>. The ferrule first end <b>78</b> is adjacent to the insulative cylinder second end <b>70</b> and extends to the cable receiving end <b>34</b> such that the ferrule second end <b>80</b> is positioned slightly forward within the annular projection <b>11</b> near the cable receiving end <b>34</b>.

[0020] Termination of the coaxial cable <b>20</b> and assembly of the connector <b>10</b> will now be described in greater detail with reference to FIGS. 3 and 4. First the dielectric <b>60</b> is loaded into the mating section <b>12</b><i>a </i>from the mating end <b>32</b> until it engages the rear wall <b>52</b>. The retaining ring <b>17</b> is secured in the receiving portion <b>48</b> to retain the dielectric <b>60</b>.

[0021] To prepare the coaxial cable <b>20</b> for installation in the end connector <b>10</b>, a conventional tool is used to strip one end of the coaxial cable <b>20</b> as best shown in FIG. 1. The protective jacket <b>24</b> of the coaxial cable <b>20</b> is removed to expose the outer conductor <b>23</b>. A portion of the outer conductor <b>23</b> and a smaller portion of the dielectric <b>22</b> are <b>30</b> stripped away to expose the center conductor <b>21</b>.

[0022] The ferrule <b>13</b> is positioned over the protective jacket <b>24</b> behind the exposed outer conductor <b>23</b>. The outer conductor <b>23</b> is then folded back over the ferrule <b>13</b> as best shown in FIG. 3. The insulative cylinder <b>14</b> is positioned over the section of the coaxial cable its dielectric <b>22</b> exposed behind. The center conductor <b>21</b> is received in the signal pin body <b>15</b><i>b </i>and terminates behind wall <b>16</b>. Termination of the center conductor <b>21</b> to the signal pin <b>15</b> may be accomplished by crimping or other suitable means. The terminated pin <b>15</b>, insulative cylinder <b>14</b>, ferrule <b>13</b> and cable <b>20</b> subassembly is then inserted into the conductive outer shell <b>12</b> from the cable receiving end <b>34</b> until the pin body <b>15</b><i>b </i>engages the annular stop wall <b>64</b>. The outer conductor <b>23</b> is received in a clearance <b>19</b> between the ferrule <b>13</b> and the inner surface <b>54</b>.

[0023] A conventional crimping die, such as a hex die (not shown) is then applied to the cylindrical sleeve <b>12</b><i>b </i>to secure the coaxial cable <b>20</b> inside the connector <b>10</b> as best shown in FIG. 3. Because the annular projection <b>11</b> at the rear of the cylindrical sleeve <b>12</b><i>b </i>has a larger external diameter compared to the balance of the cylindrical sleeve <b>12</b><i>b, </i>as the cylindrical sleeve <b>12</b><i>b </i>is crimped, the die will first contact the annular projection <b>11</b>. As the crimp is applied, the annular projection <b>11</b> is forced to roll inward and toward the mating end <b>32</b> of the conductive outer shell <b>12</b>. As a result, the cable receiving end <b>34</b> of the cylindrical sleeve <b>12</b><i>b </i>has post crimp diameter which is slightly smaller than the balance of the cylindrical sleeve <b>12</b><i>b. </i>The internal deformation of the cylindrical sleeve <b>12</b><i>b </i>behind the ferrule <b>13</b> causes the internal components including the ferrule <b>13</b>, the insulative cylinder <b>14</b>, and the signal pin <b>15</b>, to be biased forward. The forward biased internal components, as well as the outer conductor <b>23</b> are locked in place by the internal surface of the annular projection <b>11</b> at the rear of the cylindrical sleeve <b>12</b><i>b. </i>

[0024] As the die continues to crimp the cylindrical sleeve <b>12</b><i>b, </i>the cylindrical sleeve <b>12</b><i>b </i>is compressed to eliminate the clearance <b>19</b> between the ferrule <b>13</b> and the cylindrical sleeve <b>12</b><i>b, </i>securing the outer conductor <b>23</b> between the ferrule outer surface <b>74</b> and the cylindrical sleeve inner surface <b>54</b>. The major components are advantageously biased and retained in the conductive outer shell <b>12</b> by a single crimping action.

[0025] While the present invention has been described in connection with the illustrated embodiments, it will be appreciated and understood that modifications may be made without departing from the true spirit and scope of the invention. For example, the annular projection could be positioned on the cylindrical sleeve inner surface and a similar effect may be achieved. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.